Abstract : The underwater detonation of large explosive charges close by a target, produce effects that are devastating to vessels such as ships and submarines and in addition, provide a means to neutralise threat sea mines. The roles of the underwater shock wave, flow and bubble in the damage process are not as yet, clear. We present results of an experimental study visualizing the effects of underwater explosions on scaled, submerged cylindrical objects that represent submarines and sea-mines. Significant structural damage to the cylinder occurred with the passage of the shock wave. During this period, the bubble of detonation products failed to expand sufficiently to contact the cylinder. Some evidence is available to suggest that the principal damage mechanism can be attributed to shock wave interaction and not water flow effects. Cavitation was created by the response of the cylinder to the shock wave and by the reflection of the shock wave from the bubble.